"A pokemon game" could be any sort of pokemon game. It might just mean they might make those pokemon puzzle games or the 3DS like Pokemn Trozei or maybe even a remake of pokemon puzzle League/Challenge.
Though consdering the gap between the release of Pearl/Diamond & Platinum (2 years wasn't it?) they might just release the 3rd 5th Gen game (Probably might be called grey if they're going with the colour naming theme) on the 3DS which wouldn't be surprising. I doubt Nintendo and 3rd party companies wouldn't want to keep producing games on an old gaming console when people are more likely to buy the 3DS in the future. Though i'm sure by that time the price of the 3DS would have drop a considerable amount or they may even have released an updated version of the 3DS (DS, then the DS lite, then DSi)
Though for the Wii i hope they make another PBR that supports B&W, or even better, it should support all pokemon main series DS game that were ever released (i was upset when i couldn't transfer my Platinum team to PBR) though hopefully Nintendo would realise there mistakes and edit the pokemon restrictions for online play so that you don't always come up against people spamming Ubers, or if not that, then they should change it so that you (the player) can alter the search requirements when looking for opponents so you can edit it so you don't face people using certain Legendary pokemon (just like the Battle Tower).